Clinicopathological and molecular study of primary cutaneous CD4+ small/medium-sized pleomorphic T-cell lymphoma

Background: Primary cutaneous CD4+ small-/medium-sized pleomorphic T-cell lymphoma (CD4+ PCSM-TCL) is a rare lymphoproliferative disorder with a favorable prognosis. Distinguishing it from other cutaneous lymphomas is often a challenge. Methods: We retrospectively collected CD4+PCSM-TCL cases from two centers (MD Anderson Cancer Center, USA and University of Milan, Italy) and evaluated their clinicopathological features. Array-comparative genomic hybridization (aCGH) analysis was performed on 11 cases. Results: A total of 62 patients were identified. Single lesions were the most common clinical presentations (79%). Five patients (8%) showed multiple MF-like plaques. All patients' disease had an indolent course. The infiltrate was nodular and diffuse, multinodular or superficial but in all cases, it was characterized by small/medium pleomorphic CD4+/CD279(PD1+) lymphocytes grouped in clusters and ‘pseudorosettes’ around B-cells. aCGH analysis showed no significant genomic abnormalities. Single lesions were mainly treated with surgical excision (91%) and/or radiotherapy (95%) with low rate of relapse (12%). For multiple lesions, topical steroids, nitrogen mustard and phototherapy were mainly used but the rate of relapse was high (69%). Conclusions: CD4+PCSM-TCL is characterized by heterogeneous clinical presentations. The arrangement of atypical cells in clusters or pseudorosettes is a useful criterion for diagnosis. The absence of significant genomic alterations is in agreement with its indolent behavior.